Double-layer heterostructures were studied. The energetic influence of the quasi-twodimensional materials (MoS2 and WSe2) on the electrical properties of graphene was simulated. Electron density functional (DFT) implemented into VASP program was chosen to take into account van der Waals forces. Interlayer distances were determined for the systems studied by suitable electron density functional (DFT-D2). The distance is 3.50 Å for WSe2/G and 3.45 Å for MoS2/G respectively. Energy band structures were calculated; the influence of electric field on band structure being taken into account. A quantum-mechanical simulation was performed for determining dielectric permittivity, absorption coefficient, reflected index, Brewster angle and the critical angle.